PROMIS(r) measures have been developed to provide a systematic, domain-based approach to the assessment of patient-reported outcomes (PROs) across the lifespan and disease groups; however, these instruments continue to be underutilized by the research community, including pediatric disease investigators. This PEPR proposal leverages three existing infrastructures of the Childhood Arthritis and Rheumatology Research Alliance (CARRA), Cancer Pediatric PRO Research Network, and the Crohn's and Colitis Foundation of America Partners Kids and Teens Internet Cohort to further study legacy and newly developed PROMIS measures with the goal to enhance and promote their use by pediatric researchers and clinicians. There continues to be compelling need for PRO measures that parallel disease activity, identify high-risk patients, and reflect health outcomes important o patients and families. In addition, more robust understanding of relationships between patient factors and disease burden will promote successful care approaches and improved physical and mental health and social well-being. Two research projects are proposed for our multicenter longitudinal study of approximately 1500 children with rheumatic disease, cancer, and inflammatory bowel disease. The first research project addressed the need for clinical validation of PROMIS Pediatric measures including the following 3 aims: Aim 1. Evaluate the responsiveness of the PROMIS Pediatric measures to measure change in health over time and its association with clinical anchors and patient-reported symptom toxicities. Aim 2. Evaluate whether PROMIS measures of depression and anxiety are associated with subsequent measures of health status including physical and social functioning, substance use, and disease specific outcomes; Aim 3. Determine the association between steps taken (pedometer data) and PROMIS Pediatric measures in order to explore the use of pedometry data to augment PROs in research and clinical care. The second research project addresses the need to enhance the meaningfulness and usefulness of PROMIS measures and includes the following 3 aims: Aim 4. Identify unobserved subgroups of children with rheumatic disease, cancer, or IBD with respect to physical and mental health using latent profile analysis and latent transition analysis, and examine demographic and clinical characteristics associated with the subgroup classification and transition over time; Aim 5. Estimate a clinically minimally important difference (MID) in change in PROMIS Pediatric scores from the child's perspective and compare with the previously generated estimate of an MID of 3 points from qualitative scale-judgment methods; and Aim 6. Identify clinical cut scores along the PROMIS Pediatric metric associated with varying levels of symptom severity and functional status using standard setting methods with adolescents, parents, and clinicians. The Center's Data Management and Administrative Cores include experienced clinicians, behavioral scientists, statisticians, psychometricians, and information technology experts to facilitate, coordinate, and synergize these research studies.